2-Aryl-5-(perfluoroalkyl)pyrrole compounds are useful as insecticidal and acaricidal agents. In addition, those compounds are also useful for the preparation of other insecticidal and acaricidal agents. In particular, 2-aryl-5-(perfluoroalkyl)pyrrole compounds are key intermediates in the preparation of arylpyrrole compounds such as chlorfenapyr. Accordingly, there is an ongoing search to discover new and more efficient methods for the preparation of 2-aryl-5-(perfluoralkyl)pyrrole compounds.
U.S. Pat. No. 5,145,986 discloses that 2-aryl-5-(trifluoromethyl)pyrrole compounds may be prepared from N-(substituted benzyl)-2,2,2-trifluoroacetimidoyl chloride compounds. However, certain 2-aryl-5-(perfluoroalkyl)pyrrole compounds may not be as readily prepared from commercially available starting materials using the process of U.S. Pat. No. 5,145,986.
U.S. Pat. Nos. 5,446,170 and 5,426,225 disclose that 2-aryl-5-(trifluoromethyl)pyrrole compounds may be obtained in four steps from the appropriate aldehyde. The processes described in those patents require the use of an aminonitrile intermediate which is obtained via the Strecker synthesis from the appropriate aldehyde. However, the use of the Strecker synthesis is not entirely satisfactory because of cyanide containing waste streams.
Accordingly, what is needed in the art is an efficient process for the preparation of 2-aryl-5-(perfluoroalkyl)pyrrole compounds which does not require the use of N-(substituted benzyl)-2,2,2-trifluoroacetimidoyl chloride compounds and avoids the use of the Strecker synthesis.